They referred to the initial test flights being 90 seconds in duration. I would not expecgt subsequent programmatic flights to be so short. UAVs operating in earth gravity and atmosphere easily get 20 times that flight time, and there is no physical reason why the power consumption on Mars would be even nearly that much higher, provided that the props are optimized for the 0.02 kg m⁻³ atmospheric density (i.e. 1/50 earth atmospheric density).
Flying is just one of the energy requirements for the drone -- it's going to have to send the data it records back to Earth and even using a Mars satellite to relay that is going to require a not insignificant amount of power and energy. Additionally, they'll need to use power and energy to keep it warm enough -- the low air density will limit convection loss but not eliminate it. Putting a lot of insulation on it is impractical though a radiation blanket is almost certain. At the other end getting rid of heat produce during flight will be another problem as the air is so thin convection will do little to limit temps during flight -- it is for this reason I think flight times will have to be kept short.
One way they might reduce weight and sensitivity to temp might be to use super capacitors instead of batteries as that would permit much higher power output and a practically unlimited lifespan relative to a small battery being over-driven to produce the power needed for flight. The downside to ultra capacitors is high self discharge.
Perhaps the biggest trouble area is dust and the impact that will have on solar energy production particularly given the fact that every flight will begin and end on loose dirt. The annual planet wide dust storms could pose a major problem if it zero's out energy production for a few days. One upside potential is that the props might help to blow off some of the dust from the storms -- OTH, those same props will blow up the dirt on the ground and onto the solar cells.
Brian